Monday, January 31, 2011

This 57 yo male with no past medical history had sudden onset of chest pain while sleeping. He called 911 at midnight and his prehospital ECG (unavailable) showed acute MI and the cath lab was activated 20 minutes prior to arrival, giving cath lab personnel time to drive into the hospital as the patient was being transported.

Computerized QTc was 410 ms. First ED ECG, only 1 mm ST Elevation in V2, V3, and aVL, but marked ST depression in inferior leads and V5, V6. Notice the T-wave towers over the R-wave in V2 and V3, and there is an upright T-wave in V1. In early repolarization, there are well developed R-waves in V2-V4, so this ECG cannot be early repolarization. Even without the changes in inferior and lateral leads, the hyperacute T-waves in V2 and V3 are diagnostic of STEMI. The computer missed this.

If you used the formula, you would only come up with 22.9, which is less than 23.4 (86% sensitive at this cutoff, and 90% specific), but greater than 22.0 (96% sensitive and 81% specific)

The Door to Balloon time was 34 minutes, time from symptom onset to opening of a 100% occluded wraparound (type III) LAD was about 80 minutes (very short). Nevertheless, the patient suffered a large myocardial infarction, with a peak troponin I of 290 ng/ml. There was a large anterolateral, anteroseptal, anteroapical, and distal inferior wall motion abnormality, with EF of 30-35%. The convalescent echo several weeks later will tell us how much of this is due to (irreversible) infarction vs. temporary "stunning". His follow-up ECG the next day is shown below.

There are "reperfusion" T-waves in V1-V6 and I, aVL. There is a QS-wave in V2, and QR-wave in aVL, and poor R-wave progression in V3 and V4, all diagnostic of anterolateral MI, subacute.

This demonstrates:

1) hyperacute T-waves, with loss of R-wave amplitude such that the T-wave towers over the R-wave
2) that the computer again misses a clearly diagnostic STEMI
3) that a large STEMI may not meet any millimeter criteria for STEMI (there are several published criteria, and the only one met here is 1 mm in two consecutive leads, an extremely non-specific criterion. In fact, no STE millimeter criterion has adequate accuracy)
4) that even with rapid reperfusion, much myocardium may be lost.

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Cases come from all over the world. Patient identifiers have been redacted or patient consent has been obtained. The contents of this site have not been reviewed nor approved by Hennepin County Medical Center and any views or opinions expressed herein do not necessarily reflect the views or opinions of Hennepin County Medical Center.